TEN YEAR RESULTS OF METASUL METAL– ON–METAL ARTICULATION IN TOTAL HIP REPLACEMENT

Abstract

Introduction: Total hip replacements (THR) with the first generation metal-on-metal articulation were abandoned in 1970s in favour of metal-on-polyethylene articulation. Osteolysis due to polyethylene wear particles renewed the interest in metal-on-metal articulations. The second generation had improved clearance, metal hardness and reproducible surfaces. We describe the 10-year outcome of 63 THR with Metasul metal-on-metal articulation.

Methods: From 1995 to 1996, 86 patients (90 hips) underwent THR with Metasul articulation and cemented CF-30 femoral stem. Of these, 55 hips had a cemented Stuhmer-Weber-Allopro cup and 35 hips had an uncemented Allofit cup. Eleven patients (12 hips) died and five patients (6 hips) were not available for clinical evaluation. However all had been contacted and it was known that the hip was not painful and had not been revised. Nine patients were lost to follow up. Thirty nine hips in cemented group and 24 hips in uncemented group had clinical, radiological and Oxford hip score (OHS) at minimum of 10-years follow-up after the operation.

Results: The minimum length of follow up was 10-years with an average of 10.8 years. The average OHS at 10 years for the cemented group was 23 (range 12 – 42) and for the hybrid group was 20.3 (range 12 – 37). Five out of 63 (8%) hips had revision surgery. Two revisions (3%) were performed because of infection, 1 was revised (1.5%) because of unexplained pain and suspected metallosis and 2 were revised (3%) for suspected aseptic acetabular cup loosening.

Conclusion: In comparison with the outcome of first generation metal-on-metal bearing, the hips in our study had lower rate of revision due to acetabular wear and loosening. This is the first study to show that the Metasul articulation has good outcome over a 10-year period. The survivorship is 97% with aseptic loosening as the endpoint for revision surgery.